def jia(a, b):
    return a + b


def jian(a, b):
    return a - b


def cheng(a, b):
    return a * b


def chu(a, b):
    return a / b


while True:
    print("请输入运算符：+ - * /")
    operator = input()
    print("请输入两个数字：")
    a = float(input())
    b = float(input())

    if operator == "+":
        print(jia(a, b))
    elif operator == "-":
        print(jian(a, b))
    elif operator == "*":
        print(cheng(a, b))
    elif operator == "/":
        print(chu(a, b))
